British Museum Technical Research Bulletin

Volume 2

This second volume of the British Museum Technical Research Bulletin contains articles that address the assessment, examination, treatment and analysis of objects from across the Museum’s collections and beyond, reflecting the diverse role that conservation and scientific activities play within some of the Museum’s wider programmes.

The articles focus not only on objects conserved and examined as part of gallery refurbishment programmes and temporary exhibitions, but also on the results of longer-term studies of the collection.

The Museum’s international activity is reflected in the assessment of Neanderthal skeletal remains in Krapina, Croatia, while an article about a small Egyptian glass scarab demonstrates how studies that begin with a particular (perhaps narrow) focus frequently expand to consider different aspects of the preservation and interpretation of objects.

All articles have been anonymously peer-reviewed by specialists outside the British Museum.

SummaryThe Gayer-Anderson cat (EA 64391:1947,1011.1) is one of the best known objects in the collections of the British Museum’s Department of Ancient Egypt and Sudan. It is a life-size cast copper alloy figure of a cat sitting upright, probably dating to the Egyptian Late Period (around 600 BC). Despite the iconic nature of the sculpture no scientific or technical examination had been made of the piece until recently. This article describes a full technical investigation within the context of the archaeological and religious significance of the figure. This revealed that the figure, although now repaired, had suffered an unexpected level of damage in the past. It also showed evidence of the original manufacturing techniques used. Indications were also found of the possible original appearance of the object, including the use of polychromy.

SummaryThe British Museum’s citole (P&E 1963,1002.1) is one of Britain’s earliest extant stringed instruments. Dating from around 1300–1330, its survival can be attributed to three factors: the quality of craftsmanship with its richly carved decorative elements, its association with Elizabeth I of England (1558–1603) and her favourite Robert Dudley, Earl of Leicester, and its modification to keep pace with changing musical fashion.

The refurbishment of the medieval galleries at the museum during 2007–2008 allowed an opportunity to re-evaluate past treatments of the instrument and investigate its present form scientifically. Throughout its history the instrument has undergone periodic repair, including the replacement of soundboards, fingerboards, strings and other fittings, but its magnificently carved boxwood (Buxus sempervirens) body, neck and headpiece remain virtually intact.

Detailed examination of the citole components prior to and during conservation revealed previously suspected but unseen alterations. Radiography has been used to study features of the original construction as well as internal alterations which show that it could have been played with a bow. The metal elements have been identified by X-ray fluorescence analysis, while microscopic analysis enabled the identification of the wooden components.

Interpreting past restorations and modifications allowed for informed judgements to be made about conservation treatments, while making more accessible important information about the instrument’s past.

SummaryThe first examples of ‘slipper coffins’ were discovered by William Kennett Loftus (1820–1858) at the site of Warka in southern Iraq in 1850. They attracted much popular attention and are one of the hallmarks of Parthian funerary practice in Mesopotamia. Similar coffins have since been excavated at other sites in this region and are displayed in several major museums. There has been previous discussion of their date and/or contents but here the first detailed discussion of the processes of their manufacture is presented. The coffins were built from a series of slabs of chaff-tempered clay, using established ceramic-forming techniques, and glazed using alkaline glazes, long used in Mesopotamia. The observations provide an indication of the skills and confidence required to manufacture, decorate and fire these spectacularly large objects.

SummaryIn 2005, the Ethiopian government’s decision to offer the fossilized remains of a three million-year old human ancestor for an exhibition tour of the United States provoked condemnation from many palaeoanthropologists. In response, the council of the International Association for the Study of Human Palaeontology passed a resolution stating that such remains should not be endangered by loan and exhibition but preserved for qualified scientific access only. This report summarizes the findings of a detailed conservation assessment of the collection of Neanderthal remains from Krapina Cave, Croatia. Examination showed that damage had occurred due to the incorrect application of resins as preservatives and adhesives, and also the moulding of specimens for casting. Resin coatings had discoloured and contracted, making it difficult to study surface features and also resulting in surface loss. Adhesive joins were often inaccurate and join edges had not been strengthened by consolidation prior to adhesion, leaving them very vulnerable to damage and further breakage. The use of casting materials such as plaster, wax and rubber had resulted in loss of the fragile surface and new breaks, or further breaks along old joins. The report concludes that human fossils may be as much at risk from researchers as when on loan to exhibitions.

SummaryAn Egyptian glass scarab (1891,0509.35: EA 22872), thought to be from the New Kingdom period, was found upon conservation to be weeping. Analysis of the glass showed it to be of an unstable composition with high soda and low lime concentrations. The composition is similar to rare items found in the tomb of Nesikhons. The weeping salts were found to be predominantly sodium formate (methanoate) produced as a result of off gassing from the storage environment. The analysis and conservation of the scarab are described and recommendations made for future storage of the object.

SummaryThe photo-ageing behaviour of the artists’ pigments chrome yellow, alizarin crimson, orpiment, realgar, Prussian blue and Antwerp blue was examined under anoxic conditions. Watercolour paints were applied on Whatman filter paper and photo-aged in air, airtight enclosures and anoxic enclosures using ultraviolet-filtered light for more than 30 Mlux hours. It was observed that anoxic conditions had no effect on the fading process for the chrome yellow and realgar paint samples. In contrast, the alizarin crimson and orpiment paint samples faded considerably less under anoxic conditions than in air. Airtight enclosures were also found to reduce fading for these samples, although not to the same extent as anoxic enclosures. This was probably due to oxygen depletion inside the enclosures. When photo-aged under anoxic conditions, the Prussian blue and Antwerp blue paint samples faded considerably more than in air. The same trend was observed for the samples aged in airtight enclosures. In addition, all the samples of Antwerp blue paint faded significantly more than those of Prussian blue.

SummaryMummy portraits found in Roman Egypt represent a fusion between Egyptian religious rites, Roman artistic style and Greek cultural traditions. They are considered to be the only survivors of the renowned Graeco-Roman tradition of painting using tempera or wax (encaustic). Revealing the full spectrum of northern Mediterranean influence on these mummy portraits has fascinated scholars for a considerable period of time. Many of the portraits show overt Graeco-Roman influences on the way in which the individual’s costume, hairstyle or jewellery has been depicted, as well as in their physiognomic traits. However, such influence is far more extensive than artistic style alone; scientific investigation at the British Museum has revealed that much of the wood selected for the mummy portraits is not local Egyptian timber but northern Mediterranean and is heavily reliant on lime wood. Some of the pigments identified e.g. red lead (minium, lead tetraoxide) were probably not used in Egypt prior to the Roman period. This paper provides an updated summary of the scientific results of wood and pigment research, not only from the mummy portraits in the BM collections, but from the wood samples from collaborating museums, galleries and academic institutions. Special mention is made of the analysis of pigments from the six famous paint saucers excavated by Petrie at Hawara. The scientific results have shed new light on the technology, composition and history of these extraordinary ancient faces, popular from the first century AD for 200 years.

SummaryA Spanish ‘set’ of silver and silver-gilt liturgical furnishings in the collection of the British Museum is recorded as being mid-fifteenth century in date. Doubts, however, were expressed about the disparities in style and decoration of the pieces, the construction methods and, therefore, the attribution and date of the set. As part of a reassessment of the collection in preparation for a new Medieval gallery, conservation treatment, a technical examination and a scientific analysis were undertaken.

The conservation treatment principally consisted of removing an old protective coating with solvents. Where possible the objects were dismantled to assist the treatment and examination. Details of construction, tool marks, wear and old restoration were recorded. All pieces except the paten show evidence of either repair or alteration. Scientific examination of the enamels was carried out by X-ray fluorescence spectrometry. The presence of chromium and the high lead content of the glass are typical of nineteenth-century enamelling, confirming that alterations were made to the set during this period.

The stylistic evidence, taken in conjunction with documentary evidence, technical examinations and scientific results, indicate that the seven pieces appear to have been ‘enhanced’ at some stage in the nineteenth century to form the present ‘set’.

SummaryThe woods of 15 Egyptian wooden archery bows from the collections of the British Museum, ranging in date from the Neolithic period to the New Kingdom have been scientifically identified. The objects studied included bows from Asyut and from the tomb of Mentuhotep II at Deir el Bahri. Microscopical examination of millimetre-sized samples revealed all of the bows were made from indigenous Egyptian woods. Acacia (Acacia sp.) and sidder (Ziziphus spina-christi) woods were preferentially selected, with seven bows of acacia and six of sidder. These woods have a high proportion of the properties needed for optimum functioning as archery bows, i.e. resilience, flexibility, elasticity and strength. Tamarisk wood (Tamarix sp.), a less suitable choice of timber for bows, was used for the remaining two artefacts.

Across Europe, the Mediterranean region and the Middle East, three main forms of bow have been recognized. The earliest form, the self bow, was made from a single piece of wood, often a long stave to allow additional draw length. The use of a single piece of wood reduced the risk of mechanical weakness or fracturing. The other two forms of bow were backed bows (made from two layers of wood glued together) and composite bows, the most sophisticated form, in which the wood was bonded to other materials such as antler, horn and sinew. With the exception of one, whose attribution as a bow is uncertain, the artefacts in this study are self bows.